ASTM A320 Grade L7 DIN 912 Socket Head Cap Screws (2024)

FAQs

What is ASTM A320 grade L7 equivalent to? ›

ASTM A320 Grade L7 Chemical Composition

The chemical composition is equivalent to Alloy A286 or UNS S66286 stainless steel used as a raw material to produce 660 bolts, studs and nuts. Note : Typical steel compositions used for this grade include 4140, 4142, 4145, 4140H, 4142H, and 4145H.

ASTM A320 Grade L7 is a standard specification for high tensile 4140 alloy steel bolting materials, intended for use in low temperature services. The term "bolting material" as used in this specification covers, rolled, forged or strain hardened bars, bolts, screws, studs and stud bolts.

Socket head cap screws are not grade designated as are hex head cap screws. A standard inch series socket head cap screw is 20% stronger than a Grade 8 hex head cap screw and 50% stronger than a Grade 5 hex cap screw. The tensile strength is a minimum 180,000 psi for sizes 1�?

This standard specifies product grade A hexagon socket head cap screws with metric screw threads and thread diam- eters from 1.4 to 100 mm ¹), If, in exceptional cases, the screws are to meet requirements other than those given in this standard, these shall be selected in accordance with the appropriate standards.

ASTM A320 possesses several fastener grades manufactured from either alloy or stainless steel and are intended for cold temperature applications. Both Grade L7 and L7M are manufactured from a quenched and tempered alloy steel.

RE: Differencies between ASTM A320 L7M and ASTM A320 L7

The difference is that L7M is required to be tempered at 620 [°]C minimum, which reduces the mechanical properties, but improves toughness and resistance to embrittlement. L7M can meet NACE requirements for use in sour service.

Nuts: The compatible nuts for use with A320-L7 are either ASTM A194 Grade 4 or A194 Grade 7 heavy hex nuts.

ASTM A320 Grade B8 Class 2

100,000-125,000 PSI Tensile Strength.

L7 bolts are similar to B7 bolts, but they are made from a heat-treated chromium-molybdenum-tungsten alloy steel. They have a higher tensile strength than B7 bolts, with a minimum of 150,000 psi, and are commonly used in heavy-duty applications such as structural steel connections and large equipment.

Hex cap screws must meet specific tolerances as described under ASME B18. 2.1-1996. The most common specifications for hex head cap screws include ASTM A449 & SAE J429: Grade 2, Grade 5 & Grade 8. Hex cap screws are commonly mistaken for hex bolts, but differ in many ways, including the way they are installed.

What is the strongest socket cap screw? ›

The strongest socket head cap in the world

However, BUMAX fasteners are different as they offer the best of both worlds – corrosion resistance and ultra-high strength. BUMAX products such as socket head cap fasteners provide engineers with ground-breaking solutions for the most demanding fastener applications.

Key Differences

Head Design: Cap screws have a large, flat hexagonal head, while socket screws have a cylindrical head with a hexagonal socket. Installation Tool: Cap screws require a wrench for installation, whereas socket screws require an Allen wrench or hex key.

DIN 912 and ISO 4762 are equivalent standards, with the only difference in the standards themselves being that some nominal sizes were cut and that a fine thread standard (ISO 12474) was created.

DIN 912 Socket Head Cap Screws come standard with a thread length that is a function of the diameter of the thread. Metric & Multistandard Components Corp. stocks a range of longer Socket Head Cap Screws that are Fully Threaded that otherwise match the DIN 912 specifications.

DIN stands for “Deutsches Institut für Normung“, meaning “German institute for standardisation”. National standards (DIN) will be/have been largely replaced by international/European standards. DIN standards are still valid for products having no ISO or EN standards.

With near-identical chemical properties, B7 and L7 differ in their testing requirements - ASTM A320 L7 bolting is specified for low-temperature service, and as such has additional impact-testing requirements. The "M" suffix designates a lower maximum hardness and tensile strength.

Originally approved in 1948, the ASTM A320 specification covers alloy steel and stainless steel bolting materials for low temperature service.

L7 bolts are similar to B7 bolts, but they are made from a heat-treated chromium-molybdenum-tungsten alloy steel. They have a higher tensile strength than B7 bolts, with a minimum of 150,000 psi, and are commonly used in heavy-duty applications such as structural steel connections and large equipment.

L43 bolts can be as large as 4” in diameter, whereas Grade L7 does not exceed 2-1/2” diameter. L43 strength and chemical properties are virtually identical to L7 but may perform more favorably with regard to Charpy impact testing.